CIE Nov 2013 v3 Paper 4 Q7

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Examiners For Use 14 Section B Answer all the questions in the spaces provided. (a) Enzymes are particular types of proteins that catalyse chemical reactions. The ef ciency of enzymes can be reduced by the presence of other substances known as inhibitors. (i) State one example of a substance that can act as a non-competitive inhibitor in enzyme reactions.(ii) For the inhibitor you have identi ed, explain why it is a non-competitive inhibitor.(iii) The graph shows the rate of an enzyme-catalysed reaction against the substrate concentration in the absence of an inhibitor. rate of reaction concentration of substrate On the same axes, sketch a graph showing the rate of this reaction if a competitive inhibitor was present. [4]UCLES 2013 9701/43/O/N/13<br /> Examiners For Use DNA 15 (b) DNA is responsible for encoding the amino acid sequence to produce proteins. Ribosome, tRNA and mRNA are all involved in the process of protein synthesis. (i) Write ribosome, tRNA and mRNA in the boxes below to show the correct sequence in which they are involved. protein (ii) Sequences of three bases code for speci c amino acids. The code UGA however does not usually code for an amino acid. Suggest its use.[3] (c) Much of the energy used in biochemical reactions is provided by the hydrolysis of the molecule ATP. (i) What are the breakdown products of the hydrolysis of ATP?(ii) Give two uses for the energy released by ATP hydrolysis in cells. 1.2.[3] [Total: 10]UCLES 2013 9701/43/O/N/13 [Turn over<br />

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